Attempting to Strengthen Front Axle For 40's?

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T

TOYSTRY

Joined
Nov 3, 2023
Threads
7
Messages
31
Location
Bend, OR
I’ve been building this rig over the past three years specifically for Moab and Rubicon-style wheeling. I’ve run Moab successfully the last two years on 37s, but lately I’ve been seriously considering stepping up to 40s.

My current setup
  • Dobinson 4" MRR Suspension
  • Yukon 4.88's
  • Eaton Lockers
  • SLEE Steering Arms
  • Sumo Hi/Low TC Gears
  • Delta Radius Arms
  • Delta Panhard Correction
  • + some other things I'm probably forgetting.
Thinking these are the next items on my to-do list.
  • Cutting fender wheels as we speak to make more clearance
  • RCV 30 Spline
  • Hydro assist (Trail Gear)
  • Steering box reinforcement (recommendations?)
  • High steer system (Front Range or Hellfire)
  • Housing gussets/truss (recommendations?)
 
Your list seems pretty decent to run 40s. I do have to ask, how hard are you wheeling? Moab can go from easy to ridiculous, and Rubicon can be done in IFS rigs, but there's plenty of places to destroy a buggy if you tried hard enough.

I would go with knuckle ball gussets for sure. I think DeltaVS makes frame plates to strengthen around the box. A 105 secor shaft would be a good idea as well. You can have Redhead rebuild your box with one and add hydro ports while they're at it.

For me, the biggest weak link was still the hp8 front diff. I know if you're careful you can get away with a lot, and many do. Just keep that in mind. I went to a RuffStuff 9.5 housing up front, and now I'm going 1 tons. Should have done that originally, but I'm a glutton for punishment.

BTW, unless you have ugly fenders, don't trim until you have tires on and suspension where you like. It's easy to overdo it. Just look at mine :rofl:
 
tmxmotorsports said:
@Broski This is you area what should op add
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I would truss the housing and like @AgentOrange said do the knuckle gussets.
And be careful in reverse 😎
 
tmxmotorsports said:
So what your saying is don't use reverse lol
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No what I’m saying is don’t try to pull someone who’s stuck out in reverse. Like wise don’t try to back up a gnarly, obstacle in reverse either.
Unless you want that high opinion 8” differential to go boom😉
 
Broski said:
No what I’m saying is don’t try to pull someone who’s stuck out in reverse. Like wise don’t try to back up a gnarly, obstacle in reverse either.
Unless you want that high opinion 8” differential to go boom😉
Click to expand...

It’s also horrible for the transmission, especially with a manual. Meaning, reverse is the weakest gear in the trans.

Cheers
 
For bracing the frame and steering I'm making new 3/8" steel front crossmembers that tie the steering box, frame and panhard bar solidly into the passenger frame rail.

20260401_161258.webp


20260401_161313.webp
 
NorthWA said:
Where are you all sourcing best knuckle gussets? Or DIY?
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Arc fab has some nice units check them out. Or on the cheap you can use thick AF angle iron and shave to fit. But I think the Arc fab units are 50$ish just make sure who ever is welding them knows what they’re doing cause that’s an expensive mistake if you goof it up. It’s been suggested to me heating up the knuckle ball prior to welding and cooling it off slowly is the move cause the knuckle is a cast item and extra precautions are needed. Anybody else have opposing views? I’d like to know.
 
MissahPapaJ said:
Arc fab has some nice units check them out. Or on the cheap you can use thick AF angle iron and shave to fit. But I think the Arc fab units are 50$ish just make sure who ever is welding them knows what they’re doing cause that’s an expensive mistake if you goof it up. It’s been suggested to me heating up the knuckle ball prior to welding and cooling it off slowly is the move cause the knuckle is a cast item and extra precautions are needed. Anybody else have opposing views? I’d like to know.
Click to expand...

I used to narrow diffs and build housings.

When you weld on a housing you're gonna warp it. Just physics.

Anything important I always made pucks for the Carrie bearing bores and slid a straight piece of TGP through to check end alignment.

Heat straighten with a rosebud.
 
MissahPapaJ said:
Arc fab has some nice units check them out.
Click to expand...
These guys?
www.arcworxs.com

80 series knuckle gussets — Contact us

The 80 front axle housing is prone to bending (where the knuckle ball meets the axle housing) when you start wheeling hard, especially when you have 37s-40s. Adding a gusset to this section of the housing can give a large improvement in strength and piece of mind. THIS IS A WELD ON KIT. WELDING
www.arcworxs.com www.arcworxs.com

I found these as well and emailed them about a week ago to get some better photos.
hotmetalfab.com

Toyota Land Cruiser Knuckle Ball Gussets

Reinforce your 1990-1997 Toyota Land Cruiser with heavy-duty knuckle ball gussets for improved front axle strength and durability.
hotmetalfab.com hotmetalfab.com
 
TBH, if you want to run 40s and do hard trails, you might be time and money ahead to run 1-tons. Obviously, people make the Toyota stuff survive, but you should be able to build one tons cheaper that will take some serious thrashing. Just my .02 cents.
 
PIP said:
I used to narrow diffs and build housings.

When you weld on a housing you're gonna warp it. Just physics.

Anything important I always made pucks for the Carrie bearing bores and slid a straight piece of TGP through to check end alignment.

Heat straighten with a rosebud.
Click to expand...
1779028626888.webp

Go slow small welds and use precaution
 
NorthWA said:
These guys?
www.arcworxs.com

80 series knuckle gussets — Contact us

The 80 front axle housing is prone to bending (where the knuckle ball meets the axle housing) when you start wheeling hard, especially when you have 37s-40s. Adding a gusset to this section of the housing can give a large improvement in strength and piece of mind. THIS IS A WELD ON KIT. WELDING
www.arcworxs.com www.arcworxs.com

I found these as well and emailed them about a week ago to get some better photos.
hotmetalfab.com

Toyota Land Cruiser Knuckle Ball Gussets

Reinforce your 1990-1997 Toyota Land Cruiser with heavy-duty knuckle ball gussets for improved front axle strength and durability.
hotmetalfab.com hotmetalfab.com
Click to expand...
1- yup those guys my bad I should’ve looked up the actual name

2- If you have a grinder and some stout angle iron you can make those yourself with a little massaging. I’ve seen I few people do angle iron braces here and there.
 
PIP said:
I'm more of a burn it in hot and straighten it later type of fabricator.

I'm a better at machining and bending stuff than welding.
Click to expand...
You ever modify a 80 series full float rear axle housing adapted for late 80’s-90’s yota pick ups? Always thought that would be the shizz. I’m not a fan of semi float designs.
 
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